Alternating-current dynamic indication system



sepwzs 192e.` 1,601,375

y P. X. RICE ALTERNATING CURRENT DYNMIC INDICATION SYSTEM Filed March1o. 192:5

1v NTO-IR.

ATTORNEY.

rai-@aaa sept. 2s, 192e.

illtll'll' STATES racista PATENT osi-ics PHILIP X. RICE, OF STATECOLLEGE, PENNSYLVANIA, ASSIGNOR TO GENERAL RAIL- WAY SIGNAL COMPANY, OFROCHESTER, NEW `YORK.

Application filed March l0, 1923. Serial No. 624,265.

rIhis invention relates to interlocking systems, and particularly tomeans :tor obtaining a reliable indication as to the position ot atraitic controlling device.

In electric interlocking systems commonly used, at least two particulartypes ot electrical indication have been used, namely (l) systems inwhich certain circuits are closed which include a constant supply otenergy when an indication is to be given; and (2) systems transmittingenergy of a distinctive character in a closed circuit inomentarily, thisenergy vbeing derived trom the motor of the tratiic controlling devicewith which it is associated (such as a switch Y machine, semaphoresignal or derail) as the motor decelerates at the completion of anoperating cycle. This latter type ot system is comercially known as adynamic indication system, and it is to this latter type oi system thatthe present invention particularly relates. Y Y

lynainic I indication has been 'successfully employed .tor operatingswitch machines and derails, which must be positively driven to thenormal and alsoV to the reverse position, and wherein the dynamicindication current is generated after the motor has operated the traiiiccontrolling device into one or the other position as conditions mayrequire. In this application of the dynamic indication principle, theindication current is derived by the inertia 'ot the motor and itsassociated parts after it has completed the movement ot' the tratticcontrolling device. In applying the dynamic indication principle tomanually controllable electrically 0perated signals, which are onlymoved to the clear position by a motor, the indication current isgenerated by the motor when it is being -driven backwards when thesignal gravitates to the zero degree or danger position. Similarly, thissame principle ot obtaining an indication currenton the dynamicprinciple has beenapplied to signals which are automatically operated,but which nay be moved to the danger position manually. In this type otsystem, a suitable energy storing device, such as a spring, isprovided,vv'hicli is adapted to operate the signal motor providing thesignal is already assuming the normal danger position and the lever-isin the indication position.y f

- In each of the systems above mentioned in which the dynamic indiqeiOllprinciple has been applied commercially, a commutator motor has beenused, this motor being operated either by direct or alternating currentwhen used as a motor depending on its construction and the kind ofenergy available, and functioning as a direct current generator whenused to generate an indication current. In the present invention, it iscontemplated to apply this dynamic indication principle to traiiiccontrolling devices, such as heretofore mentioned, by employing analternating current motor, either ot the well-known induction type whichdo vnot require commutators or of the commutator type tor driving suchtrattic controlling device, and also tor generating an alternatingcurrentotl distinctive character at the time a` flow ci' an indicationcurrent is proper.

More speciiically, it is proposed to provide an induction motor, eitherof the polyphase or splitphase type for actuating the tra Liccontrolling device to the proper position, and to energize one of thewindings ot this motor with an alternatingfexciting current. which inturn causes the generation of an alternating current in another phase otsuchl motor. This generated current being used to control a suitableelectro-responsive device, which is adapted to give a visual indication, is adapted to unlock a lever, or is adapted to carry out both ofthese functions. The` several constants of a system of this type arepreferably so chosen that the dynamic indication current will have adistinctive phase relation with respect to any current that couldpossibly be obtained byV unauthorized crosses of wires, or the like.A

Other objects, purposes and characteristic `features of the inventionwill appear as the description thereof progresses.

In describing the invention in detail, rei"- erence will be made to theaccompanying drawing in which the present invention has been applied togive an indication in connection with a lever for operating a two-posiftion signal. In illustrating the invention, the various parts have beenshown in a manner to make it easy to understand the invention, ratherthan with the view of showing the particular construction preferablyemployed in practice.

' Structure-Referring tov the drawing, a trackway` comprising rails 1has been illus'-` CFT trated adjacent to which there is shown a" signalS, which is ilianuallyxoperated from a distant tower Which vhas beenconventionally illustrated by the dotted rectangle. This signal ispresumed to protect a certain conflicting route., which has not beenshown in the drawing. Certain ot the most essential elements ol thesignal S have been conventionally illustrated adjacent thereto, so as tofacilitate the description ot the present invention Without referring tocertain other parts, Which are Well-known to those skilled in thisparticular art, and have been omitted.

ln the interlocking tower is provided a manually operable lever L, whichwith its associated parts comprises a portion ot a Well-known andcon'nner'cially used dynamic indication interlocking system, andtherefore will not be described in detail. lt may, however, be statedthat the coils l and armature 5 are parts of an indication magnet lill,Which in connection With the detent 6 is adapted to release the loclrdog Y from the locking shoulder 8 ot the lever L when this lever isbeing' operated from the reverse position toward the normal position, inwhich it has been shown. Tie lever is locked in the h alf normalposition (as shown by the dot and dash line representing the contactblock), showing the contact blocl in engagement off this lockingshoulder 8 h the locli dog 7, this locking ot the lever L in the haltnormal position persisting until an indication current is received bythe coils l ot' the indication magnetlM. A momentary flow of currentthrough these coils Ll, with the lever in the hallE normal position,causes the armature 5 oit the indication mag- .n t to be attract-editomove the detent 6 'from under the lock dog 7 whereby the spring 9 movesthe lock dog 7 to its ineffective position, thus enabling the towerattendant to move the lever L tothe full noi-'nal posit-ion, and in turnunlock cert 'n other conflicting levers, such unlocking oi conflictinglevers being cilectedby the n'iovcinent of the roller l0 associated withthe tappet bar ll to the extreme loiver position, as shown.

l should be noted that inovenien't oi" the lever L toward the lefl't,that is, toward the reverse positiondoes not cause ift to be ellectivelylocked when reachiifig the half reverse position, although 'therighthand end of the lock dog l is moved upward and reta-ined theretemporarily by theA det-ent 6. Eis Vthe lever is moved toward the lett,the projection l2 rocks` the unlocking cam l which in turn strikes thetailpieee ot' the detent 5'-, thereby unlocking this lever, rthat is,the lever L is lockedv in both, the lia-li norm -l and the'halt reverseposition, but upon moi lent of the lever toward the reverse position,

nieehanical unllcclzing tales place regardless et the condition etvthedistant traliic controldevice, that is, the signal S the prt'icular-arrangement show 5 Whereasinet.;-

nient ot the lever toward the rightv that is, toivard` the normalposition, does not permit such mechanical unlocking, the unlocking inthis instance beingv accomplished by the energization of the indicationmagnet IM.

ln the toweris` also provided an indication relay lll. This indicationrelay IR is preferably ot the tivo-element type, and may be ot eitherthe dynamoineter or the induction type. This relay has beenillustratedconventionally, as shoivn, by the local Winding l/l and the-operatingWinding 151. lt an induction type ot relay is used, thev local windinglll Will be constructed so as to be highly inductive, thereby causingthe fluir produced-by the local Winding to lag 'almost electricaldegrees behind the voltage producing this flux, so that the iioW of apower current flowing int-o the operating' Winding l5 through the Wire52 Will produce anl en'ec` tive torque to move the contacts 16 and l?toward the right for purposes more clearly explained hereinafter. On theother hand, ir" a dynamoineter type or relay is used the local Windingis constructed to be highly resistive tor the Vsaine reason, that is, sothat power current will produce an effective torque on the relay in onedirection and. current leading or lagging substantially electricaldegrees Will produce a torque in the opposite direction. VA transformerT is also provided in or near the signal. tower. rlhe signal S, amongother things,V includes the semaphore 2O adapted to be moved to theclear or l5- degree position, as shown by dotted lines, by a suitable`motor M conventionally shown comprising a rotor 2l, a highly resistiveWinding and a highly reactive Winding 23.,- Which in practice displacedsubstantially 90 electrical degrees, so that noy voltage can be induced.from one Winding into the other except by the rotation ot the rotor 2l.Associated with this signal l operated by the' semaphore shaft arecircuit controllers 25, 26 and SC. rllhe circuit controller @Slisadapted toclose a circuit tor the. hold-clear device HC shown, andcloses a circuit only' When the semaphore blade 201s in the l5 degree orclear position. The circuit controller 26 completes circuit toroperating the signal motor M to the clear position, and is closedtor allpositions ot the semaphore blade 2.()- between the zero and, say, the43, degree position.

The circuit controller SCI is? et peculiar type andV connects theresistive Windingin tiple with the inductive or reactive Windt ail-`times both the upward and do. ement of. the semaphore, e2;- cept vt lilethe' s .l XS" BOVIl'g Say:

from the l5 degree 5 degree position during itsA dov'nivar'l movement.During. this port cnw the (that is,..betivee`n the vd movement et'pleted for energizing the resistive winding of the motor M. This circuitcontroller coinprises a device which for ,convenience has beenillustrated as a disc 27 of insulating material operatively connected tothe semaphore blade, and having a projecting extension or lug 28.Suitably supported uponthe insulating block 29 is a bracket 30, havingits end bent to form a sleeve for pivotally supporting a switchoperator. This switch operator has been conventionally shown ascomprising a triangular plate 31 provided with three pins 32, 33 and 34respectively, the pin 32 serving as a support for the triangular plateand being pivotally supported in the sleeve of the bracket 30. To thebracket 30 and adjacent the end where it is supported is riveted aContact spring V35, which is adapted tov contact with one or the otherof two stationary contacts, conventionally shown by arrows.

By looking at the conventional showing of this circuit controller SC, itwill be noted that movement of the insulating disc 27 from the normaldanger position of the semaphore shown, to the 45 degree or clearposition (shown'by dotted lines), will cause the extension 2S to engagethe pin 34, thereby tilting the triangular plate 31 of the switchoperator toward the right without in any way affecting the springcontact 35. As soon as the extension 28 leaves the pin 34, thetriangular plate is returned back to its normal position shown, bygravity, or by a suitable spring (not shown). Upon return of thesemaphore 20 and the insulating disc 27 to the normal position, theextension 23 of this disc will again engage the pin 34 of the switchoperator. In this instance, the triangular plate 31 will be tilteddownward, thereby causing the pin 33 to engage the contact spring 35 andmove this contact spring towardr the left causing it to interrupt thecircuit normally closed by this spring contact and complete anothercircuit. As the insulating disc 27 reaches the 5 degree position, theplate 31 will again be free to move because the pin 34 is no longerengaged by the extension 28, thus allowing the switch operator to.assume the normal position shown, due to the tension of the springcontact exerted upon the pin 33.

The hold-clear device HC heretofore referred to may take any one of avariety of forms well-known in the art of railway sig naling, andcomprises means which if energized will hold the semaphore of the signalin an elevated position against the action of gravity, and Ausuallycomprises a suitable type of detent or brake device and has forconvenience been illustrated by the coils 37.

' Operazz'ofni-In the particular embodiment of the inventionillustrated, the local winding 14er" the indication relay IR isnormallyl energized lby the transformer T through a circuit comprisingthe secondary winding 40 of the transformer T, wires 41 and 42,V localwinding14 of the indication relay IR, wire 43 back to the secondarywinding 40.

Let us assume now that the tower attendn ant wishes to allow a train topass the signal S, and therefore moves the lever L toward the reverse orlefthand position, as shown in the drawing. As this lever is movedtoward the left, the righthand end of the lock dog 7 will be cammedupward after the shoulder 8 has moved by this end, thereby causing thedetent 6 to engage the lock dog 7 and hold it in this locked position.Further movement of the level' L toward the left at first seemsimpossible on account of lug 12 engaging .the right hand end of the lockdog 7. This, however, is not the case, because the lug 12 engages theunlocking cam 13 which in turn engages the tail piece of the detent 6and trips the` lock dog, thereby again unlocking the lever andpermitting it to be moved to the extreme lefthand or full reverse Yposition.

Vith the lever' in. the reverse position, an operating circuit for themotor M is completed which may be traced as follows Beginning at thesecondary winding 40 of the transformer T, wires 41, 42 and 56, contacts57, 3 and 58-of the signal lever L, wires 53 and 54, circuit controller26, wire 55; a multiple circuit comprising wire 63, contact spring 35,wire 62, winding 22 of the motor and in multiple therewith comprisingwire. 59,-inductive reactance 60, wire 61, and winding23 of the motor M;and frornthis multiple circuit wires 45 and 46, contact 17 of theindication relay IR, wire 47 back to the secondary winding 40 ofthetransformer T. Thecompletion of this circuit c'auses current to flowthrough the wind-r ings of the splitphase motor M; and on account of theresistive feature of one of the windings and the reactive feature of theotherL winding, the current flowing through these two windings will beconsiderably displaced in phase, and will cause the motor to .operateand through suitable gearingtnot shown)v actuate the semaphore 20 to the45 degree yor clear position.

' During this movement of the semaphore 20, when it reaches the 43degree position, the circuit controller 26Y will interrupt theenergizing circuit for the motor M. The inertia of the motor will,however, operate the semaphore to the 45 degree position,

which Ywill cause the circuit controller 25 to complete the followingcircuit r-Beginning at the secondary winding 40` of the transformer T,wires 41, 42 and 56, contacts 57, 3and 58 ofthe signal leve-r L, wires53 and `64, circuit controller 25, wire. 65,'coils 37 of thehold-cleardevice HC, wires 66 and 46, contactl17 of the indication relay 1R5'Wre47 back-to the secondarywndingof the; transformer T.V The completion otthis circuit energizesthe hold-.clear co'i-l's 37K and causes. thehold-clear device HC to: maintain 'the semaphore 20' and its associatedparts in the clear orV l5 degree position. Dui-ing this movement of thesemaphore from the danger to the clear position, thel spring switch armwas not actu-ated' for reasons heretofore given in the briet'description oil the operation ot the circuit controller SC.

Let us assume now that the tower attendant wishes. to again return thesignal S to its normal danger indicatingposition, possibly because thetrain hereto-fore mentioned 113i has passed the signal S, and anothertraini's aboutv to take a conililctin-g route, such as a siding or acrossing as wel-li understood by those skilled in the art. To do this,he will push the lever L toward the right until fit it hasl reached thehalf normal or indication position., as shown by the dot and dashposition ot the Contact block 3. In this position of the lever' L, theshoulder 8` enga-ges the righthand end of the lock' dog 7 thereby :7"preventing further movement' ot the lever toward'- the right, that is,locking the lever i-nthis position as 'far as the movement toward thenormal position is concerned. This movement ot the lever interrupts theSi circuit it-'orf the hold-clear device HC of the signal S, therebyallowing this signa-l to gravitate toward the Zoro degree or dangerposition. W'hen the signal reaches the l5 Q degree position on itsdownward movement, o tho extension 28 of the disk 27 engages the pin: 3lot the switch operator, moving the plate 31 in a counter-clockwisedirection about the pivot pin 32, thereby causing the AO, spring switcha-rmf to move toward the left in Contact' with the stationary contact68, which completes an exciting or field circuit for the winding 22 ofthe vmotor M.

This circuit may be traced from the sec y on-dary winding oi? thetrans-former T, wires 'y l1, 12' and 69, stationary Contact 68, springcontact 35, wire (52, winding 22 ot" the motor M, wires l5 and d6,Contact 17 ot the indication relay llt, wire 47 back to the secondarywinding ot the transformer T. The U )-completion ot this circuit causes'a current to flow in this circuit',- which is substantially in phasewith the voltagel ot the transformer T, this bei-ngV clue to the tactthat the winding 22 ishighly resistive.

lt should be noted that the motor was free t'orotate clueto the actionof' gravity acting on the semaphore 20l and hasreached a l`airly highspeed, somewhere in the neighborhood ot' synchronous speed ot the:smotor, by the time itv rea-ches the 15 degree position just 'referredto: 1iii/lith the motor run-ning at a high speed and' the resistivewinding energized from the transformer as just eX- plaine'dl, avoltage-v wlll be induced. 1n the other winding: 23 .of the `motor whichneonazis voltage lags substantially 180 degrees behind etti, contact 17ot the indication.relay7 l2, w-fes 1l?, i3 andl 48, contacts 419, 3 andi50 oi the switch leverL, wire 51, operating windingl of the indicationrelay llt, wires and fl, circuit controller 26, wires 5:3 and 59,inductive react-ance (i0,V wire 6l back to the winding 23 of the motorThe tlow ot this current which is substantially in phase opposition withthe voltage of the transformer, as tar as the winding 15 is concernedbut flows in the same relative directi'on in the wire 53 as ydoes vthecurrent for operati-ng the motor M, causes the relay to be energized ina manner to move the conlacts 16 and' 17 toward the left.

yEhe movement of the contact 17 toward the lot-t continues to completethe common return circuit heretofore mentioned; and the movement of thecontact 16 toward the lett completes an energizing circuit -for theindication magnet 1M, which may be traced as 'liol'lowsz-Beginning atthe secondary winding Ll@ ot the transformer T, wires Ll1 and 70,Contact 16 ot the indication relay lll., wire Z1-i, coils l ot theindication magnet TM, wire 'Z2 back to the secondary winding fl() of thetransformer T. The com- 'Jletion ot' this circuit energizes theindication magnet 1M, thereby causing the armature 5f to move upward andtrip the detent 6 to release the lock dog 7 and allow the spring to movethe lockv dog out of engagement with the shoulder 8, thus allowingmovement ot the lever L to the full normal position, and in turnallowing it to unlock other conflicting similar levers (not shown torsimplicity) Jfor reasons heretotore mentioned.

lt should be noted that the indication relf f' llly actuated toward thelett when the dynamic indication current, which lags substantially 180degrees behind the voltage ot he transformer T, was received.Conscquently, if for any reason unautl'iorized current should. beapplied to the wire 53 for instance while the lever L is in the 'fullnormal position as shown, such current may tend. toy operate the. motorM. It should, hows be noted that ai circuit of fairly low resistance,and low impedance, through the: operating winding l'oit the indicationrelay TR is present. This latter sliunting circuit would to a largeextent prevent any considerable amount of current from flowing in thewinding of the motor M, and the motor would probably not be` operated atall by this small current. On the other hand, the iiow of this currentthrough the operating Winding 15 of the relay IR would cause this relaytov be actuated in the reverse direction from thatin which it wasactuated by the dynamic indication current, because this unauthorizedcurrent, whichis presumed to have come from the secondary winding d() ofthe transformer T, is substantially in phase with a voltage of thistransformer; whereas the indication current, as heretofore explained, issubstantially 180 degrees out of phase with the volt age of thistransformer'. Consequently, the indication relay IR will now be actuatedin the reverse direction, and will cause the contacts 16 andr17 to bemoved to the right, and be latched in this position by thehooks 'T4 andI'5respectively. The hook 74 maintains the contact 17 in this latterposition, whereas the hook 7 5 does both, hold the contact 16 in theeXtreme righthand position and complete a circuit for the danger lamp R,which can be readily traced in the drawing. y

it should be notedthat this movementof the indication relay TR towardthe right, not only causes the contact 17 to be latched by the hook 74,but also causes an interruption at this point in the common return wiree6. rThus, the presence of unauthorized cur rent due to crosses and thelike,Will no longer be permitted to flow through the winding of themotor M, since the common return circuit is permanently interrupted.

.The indication relay TR is in practice housed in a suitable casing (notshown), which is preferably provided with glass walls and is sealed sothat the tower attendant cannot tamper with the relay mechanism. Ifdesired, suitable tiipping mechanism may be provided to allow theattendant to withdraw the hooks 'T4 and 7 5, to again allow the re- Alay to assume its deenergized position after having once been operatedtoward the right. This construction permits the attendant to release thehooks, thereby allowing the main return circuit to again be completed,but does not allow him to forcibly hold the common return circuitintact.

The dynamic indication system embody ing` the present invention thusaffords the generation of an alternating current having a distinctivephase relation from that obtainable from the transformer T operating thesignalrin connection with which the indication system has been shown.This conclusion is based on the assumption of a cross between the mainmotor feed wire 53 and a wire connected directly to the wirefl.

or a connection to the secondary winding L of the transformer T, due toa cross of some kind or other. Obviously, if the common return wire 46were connected to the wire L11 of the transformer, and the other side ofthis transformer winding were connected to the wire 53, the indicationrelay llt would not be actuated to the right to interrupt the commonreturn circuit on account of such a cross. A complicated cross of thischaracter is, however, highly improbable, and possibly would never occurin practice.

' Although inthe particular system illustrated an induction motor hasbeen shown for operating a distant traffic controlling device, and forin turn generating an alternatJ ing current of the proper phase relationwith respect to the source of supply for indicating that the trafficcontrolling device has reached a certain position, this principle ofdynamic indication may also be applied to systems employing alternatingcurrent commntator motors. if a conimutator type of motor is used, theiield winding may be energized by alternating current, at thetime anindication is proper, whereby an alternating current will be commutatedwhich is of the same frequency as that-flowing in the field winding.Qbviously, the same general circuit arrange ment will also besatisfactory in systems em- .ploying commutator motors.

lt should be noted that this dynamic indication systein also serves to'snub or retard the motor as the signal gravitates from the degree to the5 degree position. Ob# vously, if desired, this snubbing or dynamicbraking may be used independently of dynamic indication in systems whereindications are not necessary, or are provided in some otherI way.lAlso, it should be noted that if the speed of the motor is abovesynchronous speed, there will not only be an indication currentgenerated, but there will also be a regenerative current flowing in theexciting circuit, which will feed energy back into the secondary windingl0 of the transformer T.

Having thus shown and described one specific embodiment of the.invention, it is desired to be understood that this same dy namicindication principle may be applied to switch machine motors, derail,op'eratinmotors, and the like, and that other types of polyphaseinduction motors may be eniployed, by making various changes,modifications andadaptations, within'the scope of this invention andwithout departing from the idea of means underlying the same.`

Vhatris Idesired to be secured by Letters Patent of the United States,is

1. In a dynamic indication system, the combination with a polyphaseinduction motor having a rotor and a stator provided with onlyvtwowindings Idisplaced substantially ninety electrical degrees; and letlmeans tor giving an indication when said motor has lconipleted 'acertain lcycle ol' operation, said ymeans including anelectro-resfionsive device loperated by current generated -i'n one etsaid windings dueto an iexciting current in the other o-iisaid`windiiogs and the action oi the said rotor when rotating.

2. Tn 'an interlocking system l`t'or railways, the conibination vwith alever ot `a mecha-nically inte'rloelcdgroup ol' levers, a lock tor saidlever, el otro-responsive 4means :for releasing said lock, a distanttrailic controlling device including an induction inot'or having two'tield windings and a rotor fot the `noncommutating type controlled. `bysaifd lever, anda `circuit including one vot said windings tor'actuating said electro-responsive device when said motor has completeda certain cycle Iot operation.

3. in interlocking 4system -or railroads comprising, a llever etamecha'nica'lly tinterlocked lgroup "ot levers, la distant traliicycontrolling device, an induction motor ytor 4operating said traiiiccontrolling device :and having two windings anda rotor of thenon-coninninicating type, and means for connecting oneo-'t said windings-to'asource of `alternating current while the iother winding isconnected to said electro-responsive device when said motor hassubstantially completed its cycle 'of operation.

4. In an interlocking system A'i'orl railroads, the combination with aremote electrically controlled trailic lcontrolling 'device'controllable by a 'lever lot a' group not' mechanically interloclredLlevers through -a main wireand a -coinmon return wire; -saiid leverhavinga normal, a reverse andan'indication position a source 'ofalternating current having lone terminal connected to `-said commonreturn wire, a polarized alternating current indicating -deviceIconnected tosaid Icommon return wire and also connected lto ysaid mainwire when said lever is vin the indication and inthe normal position,said'trai'tic controlling'device including a motor operable byalternating current, and means lincluding said ymotorl for dynamicallygenerating :an alternatingindication current flowing in said main wireand said common return wire throughsaid indicating device. Awhen saidmotor has completed-'a 'predetermined cycle ot operation, which currenthas substantially the saine phase relation-with respect xto said sourceas the powericurrent flowing trom said source to/'said motor' throughsaid main wire when said vvmotorie energizec, whereby a cross betweensaid source andfsaid main wire while-s'aidina'in wire is connected tosaid indicating device "willlestablis'h, a current to actuate saidindicating device distinctively from the actuation :due to saidindication current.

5. An interlocking 'system for railroads Leone-75 comprising, "a sourceot current, an electri# call-ly operated tralilc controlling device, aleve-1' et a mechanically interloclred group oi levers ltor controllingsaid device by alternatinfgcurrent y'flowing in a main partial circuit,nn indicating device connected to said partial circuit when said leveris in a norinal'or *in an indication position, said -traii'iccontrolling device including means for enrgizing said :indicating devicewhen lthe traililc -controlling device has Ibeen actuated to the properposition by an alternating current in said mainpartial circuit fhavingsul;- st'antially the saine phase lrelation with respect to said Sourceas the alternating current derived tromsaid source for controllingsaiddevice.

"-6. An interlocking 'system `lor 'railways comprising ilevermechanically interloelied witha group et' fother levers, a distanttrailic controlli ng device, an induction motor of the usualconstruction "having two field windings and a rotor.,an 'indicatingdevice, means tor energizing both of said windings Vbyyalternating-'current-to Icause said meterte operate asa-'n induction'n'iotorand 'actuatefs'aid device to abiased position and for energizingonly 'one yet said windings by alternatingcurrent and connecting theother of said windings -to said indicating device when said traiiiccontrolling device =h`as `by Vits bias been returned substantially tolits original position, whereby said indicating device isoperated bycurrent generated bythe vrotation of said rotor in' a lield'ot'ilu'xproduced by the energized field winding when said device has reached itsoriginal position.

7.12m' 'interlocking system for railways comprising fa 'levermechanically interloclred with ag-group ot other levers, adistant traiiccontrollingfde-vicegan induction motor having two 'iield windings and arotor, an indicating device :tor locking said lever, means Aforicon'necting vsaid two *tield `windings in multiple 'to a'sou'rce ofalternating current to cause saidinotor to operate as aninduetionmotorand actuate said 'traine' controllingl i device,enter-connecting one ot'said windings tosaidsource oi alternatingcurrent to said source of alternating current ory to said indicatingdevice, and means including said motor effective when said tralliccontrolling deviceI has reached a predetermined position for generatingan alternating cu rrent having a phase relation to actuate saidindicating device in the reverse direction than it would be actuated ifa cross should occur between said main wire and said source ofalternating` current while said main wire is connected to saidindicating device.

9. A dynamic indication and cross protection system according to thepreceding claim, further characterized by the provision of means tointerrupt the continuity of the common return wire by operation ofJ saidindicating device due to 'such a cross.

l0. A dynamic indication and cross protection system for railwayscomprising, a traliic controlling device, a motor for operating saiddevice, a partial circuit, a lever for connecting said motor to a sourceof alternating current energy, or to an alternating current polarizedindicating device through said Partial circuit, and means including saidmotor for generating an alternating current when said motor hascompleted a predetermined cycle of operation flowing through saidpartial circuit and through said indicating device, which is displacedless than ninety electrical Adegrees with respect to the voltage of saidsource from the current iiowing when said motor is connected to saidsource, whereby said indicating device acilitates a distinctiveindication responsive to a current displacedmore than ninety electricaldegrees from said operating current.

l1. A dynamic indication and cross protection system according to thepreceding claim, further characterized by the provision of means tointerrupt the continuity of the common return wire by said indicatingdevice when such a distinctive current flows through said indicatingdevice.

l2. A dynamic indication and cross protection system for railwayscomprising, a traffic controlling device including a motor, a partialcircuit including a main wire, said traiiic controlling device and acommon return wire, a source of alternating current having one terminalconnected lto said common return wire, an alternating current in-`dicating device of the polarized type having one terminal connected tosaid common return wire, a circuit breaking 'device in said commonreturn wire governed by Said indieating device, a lever adapted toconnect said main wire to said source of current or to said indicatingdevice; said polarized alternating current indicating device being soconnected in said partial circuit when the lever is in one position,that an alternating current flowing due to a cross between said mainwire and said source will cause said indicating device. to actuate saidcircuit breaking device and break-the continuity of said common returnwire.

13. In an interlocking system for railways, the combination of a lever,of a mechanically interlocked group Yof levers, a lock for said lever, asource of alternating current, an indicating device for controllingsai-d lock, a distant trallic controlling device, an induction motorhaving two field windings and a vrotor for operating said tralliccontrolling device, a common wire for carrying both the current forenergizing saidy motor and the current for actuating said indicatingdevice, and means inclu-ding said lever which under one conditionconnects said windings to said source to operate said motor and when inanother condition connects one of said windings to said source and theother of said windings to said indicating device in a manner so that thecurrent generated in said other winding due tothe lield produced by saidfirst mentioned winding and said rotor and flowing in said common wireis substantially in phase opposition to the current flowing in saidcommon wire when said motor windings are connected for operating saidmotor, said indicating device controlling said lock only when energizedby current having a component substantially in phase with the currentgenerated in said other winding.

14. In a manually operated and electrically controlled semaphore signalfor railway signalling purposes, the combination of a semaphore bladetending to assume its danger indicating position, means for operatingsaid blade to its clear position and holding it there including aninduction motor having two field windings and a rotor, a source ofalternating current, a lever which when placed in one position connectsboth lOO ol. said windings to said source of current to operate saidmotor to move said semaphore to the clear position and which if placedin another position allows said semaphore to lll) return to the dangerposition and connects one of said windings to said source and the otherto a suitable indicating device, whereby a current having a distinctivephase relation is generated in said other winding by the rotation ofsaid rotor in the eld prdduced by said energized ifield winding when thesemaphore is returning to the danger indicating position.

In testimony whereof I hereby aflix my signature.

PHILIP X. RICE.

Cil

